The present invention relates to an electric telescopic steering apparatus adapted to absorb a deviation of a screw shaft which is used for a telescopic mechanism.
An electric telescopic steering apparatus for operating a telescopic mechanism by an electric motor has been used for a vehicle. Generally, the electric telescopic steering apparatus is constructed as follows. A telescopic jacket includes one jacket (element) and another jacket (element). The another jacket is provided to be able to slide in contact with the one jacket in an axial direction thereof. One end of a screw shaft disposed substantially parallel to the telescopic jacket is supported by the one jacket, and a nut is screwed on another end of the screw shaft. This nut is supported by the another jacket. One of the screw shaft and the nut is connected with a driving means, and another of the screw shaft and the nut is held by the telescopic jacket under a rotation-locked state. When a rotation of the one of the screw shaft and the nut is driven, the another jacket moves relative to the one jacket so that a telescopic adjustment is performed.
U.S. Pat. No. 5,806,890 (hereinafter referred to as Patent Document 1) corresponding to Japanese Patent Application Publication No. 9-240492 discloses a previously-proposed electric tilt steering apparatus, although this technique does not relate to a field of telescopic mechanism. In this technique, a universal joint is used for absorbing a deviation of axis (center line) of a shaft in a tilt mechanism.